Self-aligned graphene oxide nanoribbon stack with gradient bandgap for visible-light photodetection

In this work, we demonstrate multi-bandgap photodetectors with an inherently lattice-matched structure by the natural stacking of graphene oxide nanoribbons. The stacked multilayer graphene oxide nanoribbons are produced by unzipping multi-walled carbon nanotubes. A correlation study between image inspection and photoelectrical characterization of stacked graphene oxide nanoribbon devices is performed in specific chips. Transmission electron microscopy images reveal the presence of a multilayer graphene oxide nanoribbon with gradually increasing widths, suggesting that multilayer graphene oxide nanoribbons with decreasing bandgaps could innately act as low-pass photon energy filters and serve to increase the spectral absorption window in these photodetectors. Photoelectrical measurements show visible-light spectrum absorption, which suggests that the various energy bandgaps of the multi-layer graphene oxide nanoribbons contribute toward the increased bandwidth in photon absorption. Furthermore, photo-responsivities on the order of 10 A/W with a stable photo-switching behavior as well as fast response times are observed. The response times range from 2 ms in the membrane devices down to a few hundred of ps in the suspended devices due to elimination of the substrate effect. Based upon this correlation study, we believe that this stacked multilayer graphene oxide nanoribbon structure with gradually varying widths is a promising candidate towards the development of novel high performance photodetectors and optoelectronics. Published by Elsevier Ltd.